C / 2006 W3 (Christensen)

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C / 2006 W3 (Christensen) [i]
C / 2006 W3 (Christensen) on June 25, 2009
C / 2006 W3 (Christensen) on June 25, 2009
Properties of the orbit ( animation )
Epoch:  March 12, 2009 ( JD 2,454,902.5)
Orbit type long-period
Numerical eccentricity 0.99983
Perihelion 3.126 AU
Aphelion 35980 AE
Major semi-axis 17990 AE
Sidereal period ~ 2.4 million a
Inclination of the orbit plane 127.1 °
Perihelion July 6, 2009
Orbital velocity in the perihelion 23.8 km / s
history
Explorer Eric J. Christensen
Date of discovery November 18, 2006
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

C / 2006 W3 (Christensen) is a comet that could only be observed with optical aids from 2006 to 2011.

Discovery and observation

The US astronomer EJ Christensen discovered the comet on November 18, 2006, using images made with the 0.68 m Schmidt telescope of the Catalina Sky Survey . The discovery was confirmed by further observations the following day. At this point in time, the comet had a brightness of about 18 mag and was still 8.7  AU from the sun .

For the next two and a half years, the comet continued to move towards the sun, increasing its brightness in the process. During this time he could be observed in the northern hemisphere during the whole night. From March 2009 the visibility shifted more and more to the second half of the night and the morning sky, from June it could be observed again the whole night. In July and August the brightness was around 8 mag and then slowly decreased again from September. From November onwards, the comet was only visible for a short time at dusk and from the beginning of 2010 at brightness levels below 10 mag it was only an observation object for the southern hemisphere . It could be observed telescopically there until the second half of 2011.

Images of the comet on November 22, 2008 and July 1, 2009 Images of the comet on November 22, 2008 and July 1, 2009
Images of the comet on November 22, 2008 and July 1, 2009

Scientific evaluation

In the period from 2006 to 2009, the comet was observed with the 6 m telescope of the Zelenchuk Observatory and the 2 m telescope of the Pik Terskol Observatory in Russia , and optical recordings and spectrograms were obtained. From this the production rates of CN, C 3 , C 2 , CH, NH 2 , CO + and dust at different distances from the sun were determined.

In November 2009, the comet, which was 3.3 AU from the Sun, was observed with the PACS spectrometer on board the Herschel space telescope and the measurement results compared with those obtained with the 30 m radio telescope of the IRAM in Spain and the Nançay Radio Observatory in France . After the comet had passed through its perihelion and was again 5 AU away from the Sun, it was observed again in August / September 2010 with the PACS and the HIFI spectrometer on the Herschel space telescope, in order to compare the data obtained with those of the previous observation to compare.

When the comet was about 3 AU away from the Sun, the "forbidden" spectral lines of oxygen were found with the ARCES Echelle spectrometer on the 3.5 m telescope of the Apache Point Observatory in New Mexico , and with the measurement results of others Comets compared.

Comet C / 2006 W3 (Christensen) was also examined along with 22 others by the Infrared Array Camera (IRAC) on the Spitzer Space Telescope . The production rates of CO 2 , CO and dust could be determined. A rotation period of 21 hours was also derived for the comet Christensen .

The comet was also the object of investigation on a mission of the Wide-Field Infrared Survey Explorer (WISE). The largest serial investigation in the infrared to date was carried out on 163 comets in order to obtain information on the production of CO, CO 2 and dust, as well as the sizes of the cometary nuclei .

From the available measurement results, attempts were made to determine the composition and structure of the comet's nucleus. For this purpose simulation models were developed according to which the core should be very porous and composed of medium-sized grains of around 10 µm in size.

Orbit

For the comet, an elliptical orbit could be determined from 5657 observation data over a period of almost 5 years , which is inclined by around 127 ° to the ecliptic . The comet's orbit is thus steeply inclined to the orbits of the planets and it runs its orbit in the opposite direction ( retrograde ) to them. At the point closest to the Sun ( perihelion ), which the comet passed on July 6, 2009, it was about 467.6 million km from the Sun and was thus in the area of ​​the asteroid belt between Mars and Jupiter . Since the comet did not reach the zone of the small planets, there were no closer approaches to them. It approached Mars to no less than about 362.9 million km on May 16, and the closest approach to Earth was on August 12, except for a distance of about 345.9 million km (2.31 AU ).

According to the orbital elements, which are afflicted with a certain uncertainty, as they are specified in the JPL Small-Body Database and which do not take into account non-gravitational forces on the comet, the comet was still moving on an extremely elongated elliptical orbit long before its passage through the inner solar system with an eccentricity of about 0.99883 and a semi-major axis of about 2700 AU, so that its orbit period was about 138,000 years. The comet came from the Oort cloud and possibly experienced one of its first passages through the inner solar system as a “dynamic young” comet. Due to the gravitational pull of the planets, especially due to the relatively close passages of Saturn on April 4, 2005 in about 4½ AU distance, on Jupiter on October 5, 2009 in about 2½ AU distance, and another time on Saturn on July 2nd In 2012 at a distance of about 9 ¼ AU, its orbital eccentricity was increased to about 0.99925 and its semi-major axis to about 4150 AU, so that its orbital period almost doubled to about 270,000 years.

See also

Web links

Commons : C / 2006 W3 (Christensen)  - collection of images, videos and audio files

Individual evidence

  1. ^ DWE Green: IAUC 8777: C / 2006 W3; C / 2006 U7. In: Central Bureau for Astronomical Telegrams. IAU, November 20, 2006, accessed August 10, 2020 .
  2. ↑ PP Korsun, I. Kulyk, OV Ivanova, OV Zakhozhay, VL Afanasiev, AV Sergeev, SF Velichko: Optical spectrophotometric monitoring of comet C / 2006 W3 (Christensen) before perihelion. In: Astronomy & Astrophysics. Volume 596, A48, 2016, pp. 1–10 doi: 10.1051 / 0004-6361 / 201629046 . ( PDF; 990 kB )
  3. ↑ D. Bockelée-Morvan, P. Hartogh, J. Crovisier, B. Vandenbussche, BM Swinyard, N. Biver, DC Lis, C. Jarchow, R. Moreno, D. Hutsemékers, E. Jehin, M. Küppers, LM Lara, E. Lellouch, J. Manfroid, M. de Val-Borro, S. Szutowicz, M. Banaszkiewicz, F. Bensch, MI Blecka, M. Emprechtinger, T. Encrenaz, T. Fulton, M. Kidger, M. Rengel, C. Waelkens, E. Bergin, GA Blake, JADL Blommaert, J. Cernicharo, L. Decin, P. Encrenaz, T. de Graauw, S. Leeks, AS Medvedev, D. Naylor, R. Schieder, N. Thomas: A study of the distant activity of comet C / 2006 W3 (Christensen) with Herschel and ground-based radio telescopes. In: Astronomy & Astrophysics. Volume 518, L149, 2010, pp. 1-6 doi: 10.1051 / 0004-6361 / 201014655 . ( PDF; 408 kB )
  4. ↑ M. de Val-Borro, D. Bockelée-Morvan, E. Jehin, P. Hartogh, C. Opitom, S. Szutowicz, N. Biver, J. Crovisier, DC Lis, L. Rezac, Th. De Graauw, D. Hutsemékers, C. Jarchow, M. Kidger, M. Küppers, LM Lara, J. Manfroid, M. Rengel, BM Swinyard, D. Teyssier, B. Vandenbussche, C. Waelkens: Herschel observations of gas and dust in comet C / 2006 W3 (Christensen) at 5 AU from the Sun. In: Astronomy & Astrophysics. Volume 564, A124, 2014, pp. 1–13 doi: 10.1051 / 0004-6361 / 201423427 . ( PDF; 1.70 MB )
  5. ↑ AJ McKay, NJ Chanover, JP Morgenthaler, AL Cochran, WM Harris, N. Dello Russo: Forbidden oxygen lines in Comets C / 2006 W3 Christensen and C / 2007 Q3 Siding Spring at large heliocentric distance: Implications for the sublimation of volatile ices . In: Icarus. Volume 220, 2012, pp. 277-285 doi: 10.1016 / j.icarus.2012.04.030 .
  6. ^ WT Reach, MS Kelley, J. Vaubaillon: Survey of cometary CO 2 , CO, and particulate emissions using the Spitzer Space Telescope. In: Icarus. Volume 226, 2013, pp. 777-797 doi: 10.1016 / j.icarus.2013.06.011 .
  7. ↑ JM Bauer, R. Stevenson, E. Kramer, AK Mainzer, T. Grav, JR Masiero, YR Fernández, RM Cutri, JW Dailey, FJ Masci, KJ Meech, R. Walker, CM Lisse, PR Weissman, CR Nugent, S. Sonnett, N. Blair, A. Lucas, RS McMillan, EL Wright and the WISE and NEOWISE Teams: The NEOWISE-Discovered Comet Population and the CO + CO 2 Production Rates. In: The Astrophysical Journal. Volume 814, No. 2, 2015, pp. 1–10 doi: 10.1088 / 0004-637X / 814/2/85 . ( PDF; 2.80 MB )
  8. ↑ KJ Kossacki, S. Szutowicz: Activity of Comet C / 2006 W3 Christensen. In: Icarus. Volume 250, 2015, pp. 595-601 doi: 10.1016 / j.icarus.2014.12.019 .
  9. ↑ C / 2006 W3 (Christensen) in the Small-Body Database of the Jet Propulsion Laboratory (English).Template: JPL Small-Body Database Browser / Maintenance / Alt
  10. ↑ A. Vitagliano: SOLEX 12.1. Retrieved July 9, 2020 .